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Ultrasonic Scattering and Nondestructive Evaluation of Defects
COLORADO UNIV AT BOULDER DEPT OF MECHANICAL ENGINEERING
Pagination or Media Count:
Problems of elastic wave scattering by surface-breaking and near- surface cracks are of considerable current interest for ultrasonic nondestructive evaluation. Ultrasonic scattering by surface-breaking planar and branched cracks of arbitrary orientation is the subject of this investigation. In this paper we use a hybrid technique to study the scattering of in-plane body and surface waves by canted planar and normal surface-breaking branched cracks. We focus our attention to the near-field. Numerical results are presented for the vertical surface displacement amplitudes near the base of the crack. Model calculations show that near-field surface displacements due to scattering by planar and branched cracks are quite different even when the branches are small. Also, it is found that signatures of normal and canted cracks are very dissimilar. These characteristic differences can be used to discriminate between the various cases. Although the results presented in this report are for homogeneous medium, the technique can be generalized to study cracks in a composite medium.
APPROVED FOR PUBLIC RELEASE